Leakproof construction of tanks and the like



J. M. CROM Aug 3,, 1943.

LEAK-PROOF CONSTRUCTION OF TANKS AND THE LIKE Filed Feb. 18, 1941 Patented Aug. 3, 1943 LEAKPROOF CONSTRUCTION OF TANKS AND THE LIKE John M. Crom, Jackson Heights, N. Y. Application February 18, 1941, Serial No. 319,430

3 Claims.

This invention relates to leak-proof tanks, pipes and the like constructed of concrete combined with a cylindrical sheet metal diaphragm and held under a predetermined compression. In my Patent No. 2,315,894 dated April 6, 1943, Ihave disclosed a similar construction of concrete held under compression in two directions by a preloading system of reinforcing rods extending both longitudinally and circumferentially of the cylindrical body, whereby keeping the body always under compression in said directions and preventing the development of cracks which would permit leakage. My present invention contemplates the construction of like bodies each. incorporating an impervious sheet metal diaphragm which provides a reinforcing and leakproof medium and also serves as a form on which the body is constructed.

Concrete construction such as tanks, fiumes, pipes, conduits, etc. is largely used for storing and transferring liquids and one object of the invention is the production of improved construction of this nature and for this purpose. The invention relates more particularly to relatively large tanks and a novel and economical method of construction wherein a cylindrical sheet metal diaphragm of the desired tank size and which is to become a permanent part of the tank is employed as the form on which the tank is constructed, whereby eliminating the necessity for temporary forms heretofore required. The

method embodies the supporting of the diaphragm as a form at one face thereof while cementitious composition is applied pneumatically and in bonding engagement to the other face to form a concrete wall layer of desired thickness. The diaphragm is thereupon supported by the concrete wall and the temporary supporting means can then be removed and a cementitious layer applied in bonding engagement to the exposed face of the diaphragm. The composite tank thus constructed is thereafter placed in compression by rods on and extending circumferentially around the unit, the tensioned rods and unit being finally covered by a layer of cementitious composition applied and bonded thereto.

The preferred embodiment of the invention contemplates the supporting of rod reinforcement on and extending along the diaphragm in predetermined spaced relation from the outer face thereof before any composition is applied in compression. The production of an improved cylindrical structure of this nature and more particularly the novel method of producing the same more economically and without requiring the use of temporary forms comprises the primary object of the invention.

These and other features of the invention will be best understood and appreciated from the following description of preferred embodiments thereof selected for'purposes of illustration and shown in the accompanying drawing in which:

Fig. 1 is a fragmentary plan view of a cylindrical body being constructed in accordance with my invention,

Fig. 2 is an enlarged vertical section thereof, Fig. 3 is a fragmentary vertical section taken on line 3-3 of Fig. 1,

Fig. 4- is a fragmentary front elevational there Referring to the drawing, l0 indicates a cylindrical sheet metal diaphragm which in the construction of large tanks or the like is supported against vertical posts or studs l2, the diaphragm being constructed from sheets placed against the posts and lap-soldered at the edges to form a cylinder which is closed throughout its side wall area. The diaphragm is supported along its entire inner face by the posts l2 spaced apart about two feet and braced as at I3. A plurality of preload reinforcing rods H are then placed circumferentially around the diaphragm and held at a predetermined spacing'from the outer face thereof. While these rods. may be supported by any convenient means, I preferably employ the novel supporting elements I6 illustrated in the drawing. Each of these elements is in the form of a bolt having a hook-like outer end I! for receiving and loosely supporting the rod and a base l8 with a fiat surface to engage in face-to-face contact with the diaphragm. The supports are soldered to the diaphragm in vertical and circumferential rows spaced to receive and support the rods, as illustrated in Figs. 1 and 3, the length of the bolts being such as to space the rods the desired distance from the diaphragm.

When the diaphragm and rods are thus fixed and braced, concrete I9 is placed against the outer face of the diaphragm to a depth substantially flush wtih the rods l4, this concrete being preferably applied by a compressed air gun which is adapted to shoot semi-plastic concrete onto the form in well-known manner. The rods 14 are thus substantially buried within the concrete which is then screeded to a level with the rods, the rods being used as a guide for this operation. As illustrated in Fig. 2, the rod reinforcement 14 is supported in such relatively wide spaced relation from the diaphragm l0 that a concrete tank wall l9 of substantial thickness is formed between the rods and diaphragm.

In accordance with my invention it is also necessary that the rods shall not at this time be bonded to the concrete and. while such bonding can be prevented in various known ways, I prefer to free the rods from the concrete, before the concrete has set, by use of the tool illustrated at 20. This tool comprises a handle 20 carrying bifurcations 22 adapted to support a loop 24 of fine wire. The loop is passed around the rod and is then moved along the rod in a manner cutting away any initial bonding of the concrete therewith. Other ways of preventing the bonding include the jarring of the rods by hammer blows after the initial set, as described in my Patent No. 2,315,894, and by the use of a coating material on the rods as disclosed in Patent No. 1,818,254.

The body as thus constructed is preferably provided with a suitable liningand this can be conveniently formed as follows: The studding l2 and i3 is removed and light wire mesh 26 is attached to and somewhat spaced from the inner face of the diaphragm by light metal strips or ties 28 previously soldered to the diaphragm. A cementitious coating 30 of suitable thickness is then shot onto the mesh and diaphragm to provide the desired lining.

The concrete thus placed is allowed to harden and when it has fully set-the turnbuckles 32 are tightened to tension the rods i4 and place the concrete under the desired preload of predetermined compression, it being understood that suitable blocks or clearance is provided to permit rotation of the turnbuckles. It will also be apparent that the rods are free to slide in the supporting hooks l1 whereby tensioning of the rods compresses all parts of the tank uniformly beneath the rods. Following this tensioning operation, a substantial layer 34 of concrete is ap-' plied to the outer face of the setconcrete and to the rods in a manner and to a depth completely covering the same and bonding it into a unit body. While this stepas well as the application of the concrete to the diaphragm is most conveniently and preferably performed by the com pressed air shooting of the mixture as above stated, it will be understood that the broad aspects of the invention are by no means limited thereto.

Tanks or the like as thus constructed are held under a continuous and permanent preload compression which serves to support the tank load, strengthen the entire 'body and keep the compressed walls from cracking and chipping, the

diaphragm together with the preload rods being wholly housed within the concrete body and the diaphragm serving to stop any leakage which might otherwise occur. The tank is preloaded with a compression sufficient to prevent the concrete from going into tension even with the full liquid load in the tank. Under normal conditions, the rods remaining sufficiently stressed, the concrete wall cannot expand into a condition of tension or crack under load, and any possible leaks due to minor checking or cracking which might occur from expanding of the concrete longitudinally of the tank will be taken care of by the diaphragm.

Having thus described .by invention what I claim as new and desire to secure by Letters Patent of the United States is:

l. A method of constructing a leakproof cyasaaoio lindrical body of concrete combined with a cylindrical sheet metal diaphragm and held under compression, which consists in, erecting an im perforate and cylindrical sheet metal diaphragm and supporting it at its inner face, supporting rod reinforcement on and extending along the diaphragm in relatively wide spaced relation from the outer face thereof and free to move longitudinally relative thereto, pneumatically placing concrete against and in bonding engagement with the outer face of the diaphragm to a depth approximately flush covering the reinforcement screeding the outer face portion of the concrete to the rods by forcing a screed thereover in contact with the rods, preventing permanent bonding of the concrete to substantial length portions of the rods, stressing such portions of the rods after the concrete has set whereby placingthe body in uniform compression, and placing additional concrete over and bonded to the first named concrete and to and covering the stressed reinforcement.

2. A method of constructing a leakproof cylindrical body of concrete combined with a cylindrical sheet metal diaphragm and held under compression, which consists in erecting an imperforate and cylindrical sheet metal diaphragm, supporting rod reinforcement on and extending circumferentially about the diaphragm in substantially spaced relation from the outer face thereof and free to move longitudinally relative thereto, pneumatically placing concrete against and in bonding engagement with the outer face of the diaphragm to a depth approximately flush covering the reinforcement, said substantially spaced relation of the reinforcement being such that said depth of the concrete provides a relatively thick wall about the diaphragm, preventing the bonding of the concrete to the reinforcement while the concrete is setting, stressing the reinforcement after the concrete has set whereby placing the body in compression, and placing additional concrete over and bonded to the first named concrete and to and covering the stressed reinforcement.

3. A method of constructing a leakproof cement-lined cylindrical tank of concrete combined with a cylindrical sheet metal diaphragm and held under compression, which consists in erecting an imperforate and cylindrical shet metal diaphragm in vertical position axially, sup

porting the diaphragm in such position from'the' inside thereof, supporting a plurality of reinforcing rods on and extending along the diaphragm in relatively wide spaced relation from the outer face thereof and free to move longitudinally relative thereto, pneumatically placing concrete against and in bonding engagement with the outer face of the diaphragm to a depth approximately flush covering the rods, preventing permanent bonding of the concrete to substantial length portions of the rods, stressing the rods after the concrete has set whereby placing the concrete therebeneath in compression, placing additional concrete over and bonded to the first named concrete and to and covering the stressed rods, removing the inside supporting means, supporting wire mesh on and adjacent to the inside face of the diaphragm, and placing a cementitious lining against and in bonding engagement with said inside face and enclosing the wire mesh.

JOHN M. CROM. 

